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THOMAS E. FERGUSON AND ELMER L. LARSQN, OF CHICAGO, ILLINOIS, ASSIGNORS, BY ME$NE ASSIGNMENTS, TO ALFRED O. BLAICI-I COMPANY.

PRODUCT FOR CARBONIZING- STEEL.

No Drawing.

To all whom it may concern:

Be it known that we, THOMAS H. Fnncue soN and Emma L. LARSON, citizens of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Products for Carbonizing Steel, of which the following is a full, clear, concise, and exact description.

Our invention relates to anew product for use in connection with the increase of the carbon content of steel or iron, and a new process for increasing such carbon content.

In the arts it is highly desirable to have at hand a product which can be used the application of heat to increase the carbon content present in steel or iron. If, for instance, a low carbon steel be heated when surrounded by the product of our invention, we find that the steel takes on additional carbon, and this carbonization extends to a very material depth. In a specific case wherein we have used our product in connection with a half-inch rod, we find without carrying the heating to its limits, that carbon is introduced to a. depth of at least three-sixteenths of an inch.

Any process for increasing the carbon content is generally known in the arts as carbonization, pack hardening, cementation, or possibly by other terms. In the description herein and in the claims, we will use the words carbonizing or carbonization as intending; to mean the increase, broadly speaking, of the carbon content of steel or iron, intending this term. to include such others as those above mentioned and similar or equivalent processes.

It must be understood that one of the major uses of carbonizing consists in increasing the carbon content of low carbon steels. High carbon steels of course can be readily obtained in the market, but they do not lend themselves so readily to certain processes of manufacture or working. For this reason low carbon steels may be used which must, in order to have the required characteristics for subsequent use, have the carbon content of their periphery increased, the core or central portion preferably remaining as before with low carbon content to maintain ductility.

The product which we prefer to employ Specification of Letters Patent.

Application filed April 1, 1918.

Patented Nov. 18, 1919.

Serial No. 226,039.

is charred nut shells- We find that pecan shells, walnut shells, or other shells having similar characteristics will, when suitably charred, produce the desired carbonizing effects. We will describe specifically the use of pecan shells as one form of carrying out our invention.

When pecan shells are used to provide our product, we place the pecan shells in a suitable container and roast them over an ordinary fiame, shaking them in the meantime while the shells are thoroughly charred, having the appearance of charcoal. The shells may be ground up either before or after charring or roasting. The charring, we believe, has the effect of driving off the moisture and oils which are normally present in the pecan shells so that after roasting these shells are thoroughly dry so as not to in juriously influence the carbonization of steel or iron.

The improved product consists of these charred nut shells, specifically charred pecan shells. When these charred pecan shells, for instance, are used for carbonizing, they are packed tightly around the steel or other material which is to be carbonized and the whole is placed in a preferably sealed container and subjected to the influence of heat, which in a specific instance may be to the temperature of 1650 F. This heating is continued, but varies quite largely, depending upon the material acted upon, and it may be all the way from one hour to several days. The steel that is thus carbonized has additional carbon introduced into its pores, thus placing the material acted upon in such condition that it may be the more readily tempered or hardened. The principal ob ject, as before stated, is to increase the carbon content of the steel.

We believe that the reason why pecan or other similar nut shells are so well adapted for the above use is due to the fact that during the process of carbonization the charred shells throw off gases which, permeating the pores of the steel, introduce the carbon therein.

We have conducted extensive experiments and find that we are enabled by the use of the product herein disclosed to effect carbonization in a much shorter time than has hitherto been possible, and that we are enabled even in this shorter time to bring about a more enhanced carbonization or the steel.

It must be understood, naturally, that We do not mean to say that the carbonizing material which is to be used must consist in its entirety of our new product, as satisfactory results can be obtained by the use of our improved product as an ingredient with other products, as part of a mixture adequate for the purpose.

From what has been thus described, the nature of our invention will be readily clear to those skilled in the art, as will alsoits various modifications and adaptations.

Having however thus described one form which our invention may take, what we claim as new and desire to secure by Letters Patent is:

1. A product ingredient for increasing the carbon content of steel under the influence of heat consisting of charred pecan shells.

2. A product ingredient for increasing the carbon content of steel under the influence of heat consisting of charred pecan shells which are substantially free from moisture 0r oils.

In witness whereof, we hereunto subscribe our names this 28th day of March, A. D.,

THOMAS R. FERGUSON. ELMER L. LARSON. 

